public class MobileAppSelectAppDescController{
    
    public List<Transaction_Types__c> applicationDescriptionList {get; set;}
    public String selectedApplicationPackage {get; set;}
    public String selectedApplicationType {get; set;}
    
    public MobileAppSelectAppDescController()
    {
        selectedApplicationPackage = ApexPages.currentPage().getParameters().get('pack');
        selectedApplicationType = ApexPages.currentPage().getParameters().get('type');
        
        applicationDescriptionList = new List<Transaction_Types__c>([SELECT Id, Transaction_Description__c
                                                                     FROM Transaction_Types__c 
                                                                     WHERE isMobile__c = True AND Active__c = True  
                                                                     AND Application_Package__c = :selectedApplicationPackage 
                                                                     AND Application_Type__c = :selectedApplicationType
                                                                     ORDER BY Transaction_Description__c]);
    }
}